Passage of Medical Marijuana Laws (MML) in 28 states in the US has redefined public health due to an increased prevalence of illicit marijuana use and disorders linked to marijuana use.
While marijuana exhibits very low acute toxicity, morbidities related to use of marijuana are a major public health concern. Users who are dependent on marijuana are at a higher risk of experiencing short-term memory impairment, mental health issues and respiratory diseases. Common health indications among habitual marijuana users include poor sleep, anger, depression, anxiety, psychosis, relationship problems and respiratory issues. Potential health risks include stroke and heart attack and adverse acute and chronic effects of marijuana, at least in vulnerable populations such as adolescents, pregnant women, as well as those with underlying or pre-existing cardiovascular disease or vulnerabilities and comorbid disorders. Therefore, marijuana use and marijuana use disorders are common and often co-occur with other substance use disorders and mental health conditions.
Several studies have identified increased prevalence of marijuana use and disorders associated with use of marijuana in states that passed MML. However, there is a paucity of studies showing differences before and after MML using national data prior to MML, differentiating between early and late MML and examining data from particular states. A group led by Deborah Hasin of Columbia University examined data from three cross-sectional US adult surveys and found that between 1991-1992 and 2001-2002, illicit use of marijuana decreased with little change in disorder. With passage of MML, between 2001-2002 and 2012-2013, use of marijuana and cannabis use disorders increased.
Examining the trend in specific states of the US, during the same time period showed an increase in predicted prevalence of illicit use by 3.6 percentage points and an increase in predicted prevalence of cannabis use disorders by 1.6 percentage points in states that have MML. Two other models examining the change during an earlier period (1991-1992 to 2002-2002) and later period (2001-2002 to 2012-2013) showed interesting trends that reflect the laws related to medical marijuana, set in various states. When California was excluded from the analysis, there was an increase in prevalence in the early period, which resulted in increased illicit use and disorders, while nationally there was a decrease. During the late period, there was a significant increase in illicit use and disorders.
Results of the study show that policy changes with regard to medicinal marijuana and proliferation of dispensaries contributed to an increase in disorders associated with illicit use of cannabis. The increasing prevalence of use in states with MML may be due to increasing availability, potency, perceived safety/acceptability, liberal and permissive attitudes favoring substance use.
In 2015, 21% of Canadian youth and 30% of young adults reported using marijuana, rates that are considered amongst the highest in the world. With the legalization of recreational marijuana use in 8 states since 2012 in the US and that of Canada in 2018, investigating the effects of laws favoring sale and consumption of marijuana and its effect on overall health deserves attention.
Written By: Joseph M. Antony, PhD